Interpretive Summary: ‘Qinmei’ kiwifruit is widely produced in China. Due to extreme sensitivity to ethylene, it is difficult to maintain the storage life and fruit quality of kiwifruits. Thus, an ethylene action inhibiter, 1-MCP has been registered for application during its cold storage in many countries. Application of 0.5 µLL-1 1-MCP on ‘Hayward’ kiwifruit after harvest significantly inhibited fruit softening at 20 °C after short and medium term cold storage, without affecting soluble solids contents. Also, ‘Hayward’ kiwifruit treated with 1 µLL-1 1-MCP immediately after harvest showed a delay ripening rate and higher titratable acidity compared with control fruit within 4 weeks at 1.1 °C storage. It appears that inferior flavor, severe sourness and difficulty to ripen in ‘Qinmei’ kiwifruit treated with 1-MCP were observed in recent years by distributors, handlers or consumers in China, which lowered the local handler’s confidence in application of 1-MCP. We hypothesize that this situation may be caused by improper maturity at harvest which may influence the storage life and eating quality, and/or by excessive 1-MCP application on kiwifruit. The objective of this study was to examine effects of 1-MCP treatments on the quality of ‘Qinmei’ kiwifruit. ‘Qinmei’ kiwifruit harvested at three ripening stages were treated with 0.5, 0.75, 1.0 or 1.5 µLL-1 1-MCP before cold storage. Our study demonstrated that utilization of lower concentration of 1-MCP up to 1 µLL-1 for ‘Qinmei’ kiwifruit with intended storage of 150 days was necessary, but not for 90 days storage of fruit harvested at earlier ripening stage (harvested at 6.4 % SSC).

Technical Abstract:
Consumers and growers in China sometime complain that Kiwifruits treated with an ethylene action inhibitor 1-MCP are difficult to ripen and show poor eating quality. This study addresses the quality parameters affecting consumer preferences and reevaluates the necessity of 1-MCP application for storage of kiwifruit. ‘Qinmei’ kiwifruit (Actinidia deliciosa C.F. Liang et A.R. Ferguson) harvested at three ripening stages were treated with 0.5, 0.75, 1.0 or 1.5 µLL-1 1-MCP before cold storage. The results showed that for the fruit harvested at two later ripening stages, 1-MCP treatment reduced decay incidence after 12 days shelf life following 90 days cold storage, and the percentage of decayed fruit for 1-MCP treatment was much lower than control after 150 days storage as well as on subsequent shelf life no matter what the ripening stage was. After decayed fruit was removed from all the treatments, fruit treated with 1-MCP displayed a lower consumer acceptance, especially at higher concentrations, compared with control during shelf life. This indicated 1-MCP treated fruit presented lower eating quality compared to control fruit during the shelf life. Excessive sourness, but not firmness or soluble solids was the main factor decreasing the taste of kiwifruit treated with 1- MCP. Fruit softening was delayed by all dosages of 1-MCP. However, the higher firmness showed no significant negative effect on eating quality. 1-MCP had no influence on soluble solids content after the cold storage or during shelf life. Our study demonstrated that utilization of lower concentration of 1-MCP up to 1 µLL-1 for ‘Qinmei’ kiwifruit with intended storage of 150 days was necessary, but not for 90 days storage of fruit harvested at earlier ripening stage (harvested at 6.4 % SSC).